The present invention relates to a member used for photographic sensitive material. More particularly, the present invention relates to a member used for a photographic sensitive material that has satisfactory performance for use as an injection molding member used for a photographic sensitive material, gives no adverse effects on a photographic sensitive material, does not hurt an incinerator for scrapping it, and in the natural world, is decomposed or reduced in strength by microbes, light or heat and hence is free of the danger of causing environmental problems.
Heretofore, a member used for a photographic sensitive material, for example, a container used for an instant film (of a mono-sheet type or a peel apart type) (for example, INSTAX Mini, ACE etc., trade names), a plastic cartridge, APS cartridge, a light shielded container used for packing in illuminated room, a film unit with a lens (a wrapping member used for xe2x80x9cUTSURUNNDESUxe2x80x9d, trade name), spools, plastic cases (P cases) and so forth are injection molded from various synthetic polymers such as polyethylene resins, polypropylene resins, polystyrene resins and so forth in order to secure physical strength and also secure moisture-proof property and light shielding properties.
Further, a container used for a photographic sensitive material, a kind of the member used for a photographic sensitive material, particularly a cap of container used for a photographic sensitive material has capabilities of engaging with the body of a container, preventing the permeation of moisture, and maintaining a long shelf life as a part of the functions. Conventionally, a cap of container used for a photographic sensitive material has been produced from synthetic polymers such as low density polyethylene resins as a main material so that they can give no adverse effects on the photographic sensitive material and secure physical strength and moisture-proof property and light shielding properties.
These synthetic polymers are very excellent materials from the viewpoints of stability against light, heat, various chemicals and microbes, giving no adverse effects on the quality of photographic sensitive materials and maintaining the quality of photographic sensitive materials for a long time.
In recent years, rapid popularization of instant films and an increase in use amount of photographic sensitive materials has led to an increased demand for an injection molded member used for a photographic sensitive material having no or less adverse effects on the environment. In particular, a film with a lens (for example, xe2x80x9cUtsurundesu,xe2x80x9d trade name) is increasingly recovered, reused and recycled. However, 100% recovery is difficult in the case where it is used, for example, overseas.
Further, a cap of container used for a photographic sensitive material has been disposed of mainly by incineration or land reclamation although it has been sometimes recovered and reused after use. However, recently, an increasing attention has been paid to the issue of environmental protection and accordingly it has been demanded that a container used for a photographic sensitive material must give no or less adverse effects on the environment.
However, a member used for a photographic sensitive material made of a conventional synthetic polymer such as polyethylene, low density polyethylene, polystyrene, or polypropylene produces a lot of heat upon burning, so that their incineration in large amounts gives adverse effects on the durability of the incinerator. On the other hand, in the case where it is disposed of by land reclamation, it is stable not only to light, heat, and various chemicals but also to microbes and hence they will not be decomposed and putrefied, thus causing environmental problems.
JP 2731972B proposed the use of synthetic resin compositions that have biodegradability and/or photodegradability and generate no substance harmful to photographic sensitive materials as a wrapping material used for a photographic sensitive material. The degradable polymers disclosed in the publication contain an ester group, an alcohol group, an ether group, an amide group, a urethane bond, an imido bond and so forth. Because the polymers contain a large amount of oxygen in the molecule, they have lower combustion caloric than that of synthetic polymers such as polyethylene, polystyrene and polypropylene.
However, since the degradable polymers themselves disclosed in the publication have the above-described molecule structure, they have higher water absorption rate than that of low-density polyethylene; therefore, they can readily permeate moisture. Further, when a photographic sensitive material is contained in a member that has absorbed water, the member supplies water to the photographic sensitive material so that it is feared that the function of moisture-proofing property required for a member used for a photographic sensitive material will not be achieved.
It is known that moisture will deteriorate the performance of a photographic sensitive material. Therefore, a member used for a photographic sensitive material, for example, the body of a container used for a photographic sensitive material is made of high density polyethylene, and a case used for an instant film and a body of case used for a film with a lens are made of polystyrene, respectively. The water absorption rate of these materials are on the order of about 0.01% and at most on the order of 0.1% so that they are materials very difficult to absorb water. On the other hand, the degradable polymers mostly are highly water absorbing and it has not been elucidated yet as to what a degree of water absorption rate the material should have in order for it to be applied to a member used for a photographic sensitive material.
Furthermore, the container member used for an instant film, a film unit with a lens and so forth contain a film in a synthetic resin-made case, which is further wrapped with a moisture preventing bag. As a result, the case is wrapped in a state where the resin per se constituting the case has absorbed water. Accordingly, when the wrapping bag is left to stand at high temperatures, the humidity inside it increases so that there is the possibility that adverse effects will be posed on the photographic sensitive material contained therein. This problem, which is not encountered with in the case of a conventional member made of a resin having low water absorption, such as polyethylene, is associated with the use of a degradable polymer.
Accordingly, a primary object of the present invention is to provide a member used for a photographic sensitive material that exhibits necessary performance required for a member used for a photographic sensitive material and that does not hurt an incinerator upon incineration for scrapping it and is decomposed or reduced in strength by microbes, light or heat and hence is free from the danger of causing environmental problems.
Further, a secondary object of the present invention is to provide a member used for a photographic sensitive material, in particular a cap of a container used for a photographic sensitive material that similarly to the above does not hurt an incinerator upon incineration for scrapping it and is free of the danger of causing environmental problems and that gives no adverse effects on the photographic sensitive material in respect of engagement strength and moisture-proof property and achieves necessary performance.
To achieve the primary object above, the present invention provides a member used for a photographic sensitive material molded from a degradable polymer having a water absorption of 6% or less and a flexural modulus of 1,000 kgf/cm2 or more. Use of a degradable polymer having a flexural modulus of 8,000 kgf/cm2 or more is particularly preferable.
Further, to achieve the secondary object above, the present invention provides a container used for a photographic sensitive material, in particular a cap of a container used for a photographic sensitive material, molded from a degradable polymer having a water absorption of 6% or less and a flexural modulus of 1,000 to 6,000 kgf/cm2.